LOWER LIAS: BRISTOL. ] 37 
a section of the lowest beds of the Lower Lias at Bedmiuster 
Down.* His section is as follows: 
FT. INS. 
("Limestones and clays - - - -62 
Laminated stone with Ammonites planor bis and 
Insects - - - -07 
Zone of J Limestones and marls, with Ostracoda -45 
Am. planorbis. \ Limestone with Lima gigantea, L.tuberculata, 
Ostrea multicostata - - - -07 
Limestones and marls with Ostrea liassica ; 
[_ Insect and Crustacea bed at base - - 4 
Rhretic Beds - White Lias. 
Lima gigantea, as remarked by Prof. Tate, here seems more 
prevalent in the lower stages of the Lias than it is further south,t 
but as a rule we find only small specimens. 
We have no evidence of any mass of limestones representing 
the zone of Ammonites Bucklandi far to the west of Keynsham. 
Passing to the north of the Avon we find outlying masses of 
Lower Lias and Rhsetic Beds; and the Lower Lias overlaps on 
to the Carboniferous Limestone west of Horfield and Alveston, 
showing that promontories or islands of the older rocks stood out 
an the Liassic seas. The Bristol Coal-field itself was no doubt 
covered at one time by the higher beds of the Lower Lias. 
W. W. Stoddart has described the beds at Ashley Down, 
Montpelier, and Gotham. At the first-named locality, the zone 
of Ammonites Turneri, consisting of shales 2 feet 3 inches in 
thickness, is exposed. The zone of A. Bucklandi, which is just 
reached at the Ashley Down Quarry, is passed through at the 
Montpelier Quarry. This zone consists of limestones and shales, 
about 22 feet in thickness. The zone of A. planorbis beneath, is 
worked at the Montpelier Quarry and at Gotham, It consists 
of shaly beds and limestones ; and at Gotham the White Lias is 
reached.:}: Avicula cygnipes is found at Montpelier; and this fossil 
seems most abundant in the lowest beds of the Lias in this area, 
at Aust, &c. Ammonites Johnstoni occurs at Gotham. 
The basement-beds of the Lower Lias have been opened up 
at Horfield, near Stoke GifTord and Alveston. From Horfield, 
Bristow obtained A. planorbis, Ostrea liassica, spines of Cidaris, 
&c. ; also, in higher beds, remains of Gyrolepis, Pholidophorus, and 
Ammonites laqueolus (tortilis).^ A. angulatus has also been found at 
Horfield. 
In some portions of the Bristol area, the Lower Lias appears to 
rest directly on a bed resembling the Landscape or Gotham 
Marble, and Bristow then took this rock as the upper limit of the 
Rhaetic formation. At Gotham about 2 feet of the White Lias 
* Quart. Journ. Geol. Soc., vol. xxiii. p. 500 ; see also E. Wilson, Ibid., vol. 
xlvii. p. 545. 
f Ibid., vol. xxxi. p. 496. 
j Quart. Journ, Geol. Soc., vol. xxiv. p. 199. See also C. O. G. Napier, Ibid.. 
p. 204. 
A section at Horfield, showing about 28 feet, of Lower Lias, is given by Bristow 
in Vertical Sections, Sheet 46, No. 2. An analysis of Lias limestone from Stapleton, 
near Bristol, was published by A. Voelcker, Journ. Bath and W. of Eng. Soc., ser. 2. 
vol. vi. p. 225, 
